The present invention relates to fuel-propelled vehicles and, more particularly, to systems and methods for tailoring rocket exhaust plume signatures of fuel-propelled vehicles.
Fuel-propelled vehicles, such as rockets and missiles, utilize rocket motors to propel the vehicle through air and space. The rocket motors generally fall into three types, which are solid propellant motors, liquid propellant motors and hybrid propellant motors. Solid propellant motors utilize a solid fuel element or grain that is placed in a large solid combustion chamber. The solid fuel element or grain is usually bonded to the combustion chamber walls and burns away during flight. The liquid propellant motors employ liquid fuel tanks coupled to a fixed combustion chamber through one or more fuel lines. A hybrid propellant motor generally uses a fluid reactant (e.g., an oxidizer) to burn a solid fuel element or a fluid fuel element with a solid reactant, which are ignited in a combustion chamber.
Typically, the combustion chamber is connected to a nozzle assembly regardless of the type of rocket motor being employed. The nozzle can be a supersonic nozzle with a subsonic portion and a supersonic portion. The subsonic portion is connected to the combustion chamber, while the supersonic portion opens to the outside environment. The propellant is ignited in the combustion chamber producing heated gases moving at subsonic speeds. The gas is then accelerated to supersonic speed by the subsonic portion of the nozzle which decreases in diameter as the gas passes through the nozzle. The gas then reaches supersonic speed and enters the supersonic portion of the nozzle which increases in diameter as the gas passes through the nozzle and exits into the environment.
Chemical vehicle propulsion systems maximize performance by converting the chemical energy of a propellant into thermodynamic energy in the form of high temperature and high-pressure gases. For example, expanding the high temperature gases through a supersonic nozzle to atmospheric conditions generates a maximum thrust per pound of the propellants being utilized to drive the vehicle. Conventional rockets and missiles minimize the amount of mass expended external to the nozzle throat, since this is typically an inefficient use of the total vehicle mass. Therefore, when designing a rocket or missile vehicle, the propellants are usually selected to maximize the high-energy release per pound. These types of propellants usually contain toxic materials (e.g., acidic compounds, oxides of toxic minerals) that are detrimental to the environment.
Target vehicles are utilized in testing rocket and missile defense systems. These target vehicles simulate an enemy vehicle so that the rocket and missile defense system can be tested prior to implementation into the field. The rocket and missile defense systems employ optics and/or infrared technology to track and destroy the target vehicle. The target vehicles operate in a similar manner to the enemy vehicles but do not carry any explosives. Additionally, due to environmental concerns, the propellants utilized in the target vehicles are nontoxic propellants. Typically, the target vehicle signature plume is substantially weaker than the signature plume for the actual vehicle that the target vehicle is simulating. However, military standards contain requirements that demand certain standards be met when testing the optics and/or infrared components of the missile defense system. Therefore, it is desirable to provide the target vehicle with a plume signature substantially similar to the plume signature of the actual enemy vehicle, while still employing nontoxic propellants.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended neither to identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention relates to systems and methods for tailoring rocket exhaust plume signatures of fuel-propelled vehicles. The tailoring of the rocket exhaust plume signature is accomplished by injecting or spraying uncombusted fluid fuel (e.g., liquid fuel, gas fuel) directly into the exhaust plume of an ignited rocket. The injected or sprayed fuel controls or modifies the exhaust plume of the rocket, which can be defined by a plume profile. The plume profile can be selected off-line prior to implementation into vehicle or selected on-line though use of a programmed controller device. The plume profile defines one or more parameters associated with the injected or sprayed fuel, so that appropriate tailoring can be achieved. The one or more parameters can be, for example, fluid flow rate, concentration levels of the fluid and one or more additives, or measured parameters for real-time adjustments associated with the injected or spayed fuel.
In one aspect of the invention, the fuel-propelled vehicle is a self-propelled vehicle such as a liquid fuel propellant or a solid fuel propellant missile or rocket. The missile or rocket can be a target vehicle used in testing of missile defense systems. The rocket exhaust plume of the target vehicle can be modified or tailored to simulate an actual missile or rocket without using toxic materials to propel the target vehicle. If the target vehicle is a liquid fuel-propelled vehicle, the same liquid fuel supply propelling the vehicle can be employed to tailor or modify the rocket exhaust plume. The flow rate of the fuel into the rocket exhaust plume can be modified during a flight pattern due to changes in environmental and/or internal rocket conditions to more realistically simulate the actual vehicle.